Today hearing aids or hearing instruments have evolved into very small lightweight and powerful signal processing units. Naturally, this is mainly due to the very advanced development of electronic processing equipment, in terms of miniaturization, power usage etc., that has taken place during the last decades. Previous generations of hearing instruments were mainly of the analog type, whereas present day technology in this field mainly relate to digital processing units. Such units transform audio signals emanating from an audio input transducer into digital representation data that is processed in complex mathematical algorithms and transformed back into analog signals and output via audio output transducers to a user.
The transformations and the processing algorithms are realized by means of software programs that are stored in memory circuits and executed by processors. However, despite the very advanced development of processors and memory circuit technology, there are still limitations on how much processing power that can be configured in a hearing instrument. That is, presently the amount of memory that is available for software code and data storage in a hearing instrument is a limiting factor when deciding the complexity of an algorithm or the number of algorithms being able to run simultaneously in a hearing instrument.
Binaural hearing instruments are sets of two individual hearing instruments, configured to be arranged at a left ear and a right ear of a user. Such a hearing instrument set or pair can communicate wirelessly together while in use for exchanging data which provides it the ability to, e.g., synchronize states and algorithms. Typically, in present day binaural hearing instruments, each hearing instrument in a pair executes the same algorithms simultaneously.
Such solutions have a drawback in that each instrument in a binaural instrument pair need to be provided with as powerful processing capability as possible. A further drawback is a reduced battery life, since all processing circuitry parts that are required to execute the algorithms need to be simultaneously functional in both instruments. These drawbacks have been addressed in the prior art. For example, U.S. Pat. No. 5,991,419 describes a bilateral signal processing prosthesis where only one of the two units of the pair of units comprises a signal processor and sound signals are transmitted between the units via a wireless link. A drawback of this solution is that the circuitry in the unit with the signal processor requires substantially more space and power than the circuitry in the unit without the signal processor. A further drawback of this solution is that the unit without the signal processor is not able to execute the algorithms when it is disconnected from the unit with the signal processor.